U.S. patent application number 13/892381 was filed with the patent office on 2013-11-14 for method for identifying palm input to a digitizer.
This patent application is currently assigned to N-trig Ltd.. The applicant listed for this patent is N-trig Ltd.. Invention is credited to Eyal BOUMGARTEN, Arthur GERSHFELD, On HARAN, Nadav LINENBERG, Sharon PELEG, Amir ZYSKIND.
Application Number | 20130300696 13/892381 |
Document ID | / |
Family ID | 48699205 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130300696 |
Kind Code |
A1 |
HARAN; On ; et al. |
November 14, 2013 |
METHOD FOR IDENTIFYING PALM INPUT TO A DIGITIZER
Abstract
A method for classifying input provided to a digitizer sensor
includes sampling output over one or more sampling periods,
identifying a location of intentional input to the digitizer sensor
from the output sampled over the one or more sampling periods,
identifying an area of potential palm input based on the identified
location of the intentional input, and classifying output detected
in the area of the potential palm input as output potentially
obtained from undesired input to the digitizer sensor. The area of
potential palm input is defined to have a defined spatial relation
to the location of the intentional input. The output classified is
sampled over one or more sampling periods other than the one or
more sampling periods from which the area of potential palm input
is identified.
Inventors: |
HARAN; On; (Kfar-Saba,
IL) ; PELEG; Sharon; (Hod-HaSharon, IL) ;
ZYSKIND; Amir; (Natania, IL) ; GERSHFELD; Arthur;
(Akko, IL) ; BOUMGARTEN; Eyal; (Kiryat-Ono,
IL) ; LINENBERG; Nadav; (Even-Yehuda, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
N-trig Ltd. |
Kfar-Saba |
|
IL |
|
|
Assignee: |
N-trig Ltd.
Kfar-Saba
IL
|
Family ID: |
48699205 |
Appl. No.: |
13/892381 |
Filed: |
May 13, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61646377 |
May 14, 2012 |
|
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Current U.S.
Class: |
345/173 |
Current CPC
Class: |
G06F 3/0446 20190501;
G06F 3/03545 20130101; G06F 3/04883 20130101; G06F 3/041662
20190501; G06F 2203/04106 20130101; G06F 3/0418 20130101; G06F
2203/04104 20130101; G06F 3/04186 20190501; G06F 3/041
20130101 |
Class at
Publication: |
345/173 |
International
Class: |
G06F 3/041 20060101
G06F003/041 |
Claims
1. A method for classifying input provided to a digitizer sensor,
the method comprising: sampling output over one or more sampling
periods; identifying a location of intentional input to the
digitizer sensor from the output sampled over the one or more
sampling periods; identifying an area of potential palm input based
on the identified location of the intentional input, wherein the
area of potential palm input is defined to have a defined spatial
relation to the location of the intentional input; and classifying
output detected in the area of the potential palm input as output
potentially obtained from undesired input to the digitizer sensor,
wherein the output classified is sampled over one or more sampling
periods other than the one or more sampling periods from which the
area of potential palm input is identified.
2. The method of claim 1, wherein the area of potential palm input
is updated over subsequent sampling periods responsive to changes
in the location of the intentional input.
3. The method of claim 1, wherein the area of potential palm input
is defined as a dynamic area that is updated as the location of the
intentional input is updated.
4. The method of claim 1, wherein the intentional input to the
digitizer sensor is input provided by a stylus.
5. The method of claim 4, comprising determining an orientation of
the stylus and identifying the area of potential palm input in
relation to the orientation of the stylus.
6. The method of claim 5, wherein determining an orientation of the
stylus includes determining a three dimensional orientation of the
stylus with respect to the digitizer sensor as identified.
7. The method of claim 4, wherein the area of potential palm input
in relation to the orientation of the stylus is defined as an area
on the digitizer sensor covered by the stylus and a hand holding
the stylus.
8. The method of claim 4, comprising determining a moving direction
of the intentional input and defining the area of potential palm
input in relation to the moving direction.
9. The method of claim 1, wherein the intentional input is input
provided by one or more fingertip touches.
10. The method of claim 9, comprising: determining an angle of at
least one fingertip touch with respect to an axis of the digitizer
sensor; and defining the area of potential palm input in relation
to the angle of at least one fingertip touch.
11. The method of claim 9, comprising: identifying one or more
features of the at least one fingertip touch; identifying a hand
structure from the one or more features; and determining the area
of potential palm input responsive to the identified hand
structure.
12. The method of claim 9, comprising: determining the output using
more than sensing configuration; identifying an interaction area on
the digitizer sensor that is larger than a threshold size area for
identifying palm input; and defining the area of potential palm
input in the vicinity of the interaction area that is larger than a
threshold area for identifying palm input.
13. The method of claim 9, comprising sampling output using a
self-capacitance detection method and a mutual capacitance
detection method, and determining the area of potential palm input
responsive to output obtained from both the self-capacitance
detection method and the mutual capacitance detection method.
14. The method of claim 9, comprising determining a size of an area
over which the intentional input is provided over a plurality of
sampling periods, and invalidating the input as intentional input
responsive to the rate in the change of size being larger than a
pre-defined rate.
15. The method of claim 1, wherein input detected within the area
of potential palm input is refrained from being reported to the
host.
16. The method of claim 1, wherein input detected within the area
of potential palm input is reported to the host as undesired
input.
17. The method of claim 1, wherein input detected within the area
of potential palm input is associated with a reduced level of
confidence that the input is an intentional input provided by
fingertip touch.
18. The method of claim 1, wherein the intentional input to the
digitizer sensor is one of touch input and hover input.
19. The method of claim 1, wherein a size of the area of potential
palm input is a pre-defined.
20. The method of claim 19, wherein the pre-defined size is user
specific.
21. A method for classifying input provided to a digitizer sensor,
the method comprising: sampling output over at least two sampling
periods; determining an area of input based on the sampled output;
determining a change in size of the area of input over the at least
two sampling periods; and invalidating the input as intentional
input responsive to the change of size being larger than a
pre-defined threshold.
22. A method for detecting finger touch to a digitizer sensor, the
method comprising: defining a threshold level of output for
identifying a presence of a finger over the digitizer sensor;
determining a change in the digitizer sensor's impedance to ground;
and adjusting the threshold level response to the change in the
digitizer sensor's impedance to ground.
23. The method of claim 22 comprising: defining ratios between
voltage level measured in association with each junction of the
digitizer sensor when the junction is touched and a voltage level
measured in association with each corresponding junction when the
junction is untouched is used to detect touch; and applying the
threshold on the ratios to detect the presence of the finger over
the digitizer sensor.
Description
RELATED APPLICATION
[0001] This application claims the benefit of priority under 35 USC
119(e) of U.S. Provisional Patent Application No. 61/646,377 filed
May 14, 2012, the contents of which are incorporated herein by
reference in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to multi-touch digitizer
systems, and more particularly to recognition of palm input to a
multi-touch digitizer.
BACKGROUND OF THE INVENTION
[0003] Touch technologies are commonly used as input devices for a
variety of products. The usage of touch devices of various kinds is
growing sharply due to the emergence of new mobile devices such as
Personal Digital Assistants (PDA), tablet PCs and wireless Flat
Panel Displays (FPDs). These new devices may not be connected to
standard keyboards, mice or like input devices, which are deemed to
limit their mobility. Instead there is a tendency to use touch
sensitive digitizers of one kind or another. A stylus and/or
fingertip may be used for user input. In some known capacitive
based touch sensitive digitizers, input can be provided by both
touching and hovering over the digitizer with the stylus and/or
fingertip. One kind of touch sensitive digitizer is a touch
screen.
[0004] One known difficulty in user input recognition with touch
sensitive digitizers is that while a user provides input with a
fingertip, additional portions of the user's hand, e.g. palm may
also inadvertently touch the digitizer sensor and thus supply
input. In addition, a user may inadvertently provide input with a
thumb and/or palm while holding a stylus or resting a hand on the
touch sensitive digitizer. Different methods for distinguishing
between intended input and inadvertent input provided to a touch
sensitive digitizer have been proposed.
[0005] U.S. Patent Application Publication No. 2009-0095540,
entitled "Method for Palm Touch Identification in Multi-Touch
Digitizing Systems," assigned to N-Trig Ltd., the contents of which
is incorporated herein by reference, describes a method for
classifying input to a multi-touch sensitive digitizer that is
obtained from a body part, as inputs invalid for user interaction
and inputs valid for user interaction. The method includes
identifying a plurality of discrete regions of input to a digitizer
sensor, determining one or more spatial relations between at least
two of the regions, and classifying one of the at least two regions
as either valid input region or invalid input region, based on the
spatial relation determined between the at least two regions. An
invalid region can be input resulting from interaction by palm or
another body part inadvertently touching the sensor, and valid
input can be input resulting from a finger tip interaction.
[0006] U.S. Application Publication No. 2008-0012835, entitled
"Hover and Touch Detection for a Digitizer," assigned to N-Trig
Ltd., the contents of which is incorporated herein by reference,
describes a method for palm rejection for a digitizer sensor that
includes detecting characteristics of hover event and a touch event
related to the hover event. It is disclosed that spatial
characteristics of an area over which the hover event is detected
are analyzed together with characteristics of the touch event and
the touch event is either verified or rejected as an intended user
interaction based on the analysis.
[0007] U.S. Pat. No. 6,888,536 entitled "Method and apparatus for
integrating manual input," the contents of which is incorporated
herein by reference, describes an apparatus and methods for
simultaneously tracking multiple finger and palm contacts as hands
approach, touch, and slide across a proximity-sensing, compliant,
and flexible multi-touch surface. Segmentation processing of each
proximity image constructs a group of electrodes corresponding to
each distinguishable contact and extracts shape, position and
surface proximity features for each group. Groups in successive
images which correspond to the same hand contact are linked by a
persistent path tracker which also detects individual contact
touchdown and liftoff.
[0008] U.S. Pat. No. 6,459,424 entitled "Touch-sensitive input
screen having regional sensitivity and resolution properties," the
contents of which is incorporated herein by reference, describes a
touch screen panel having varied combinations of resolution and
touch sensitivity. Optionally area of the screen typically used for
highlighting and simple annotation is designed with low resolution
and high touch force characteristics, thereby minimizing processor
bandwidth and providing rejection of inadvertent touching such as
palm touch. An alternate area of the screen used for digital
signature input or for security marking input is designed with low
touch force and high resolution properties. Optionally, the small
area with the low touch force and high resolution properties may be
placed in a corner of the screen where it is unlikely to be
inadvertently touched. Either the varied screen properties may be
incorporated into the screen during its manufacture or the screen
may be designed so that the varied properties are programmable by
the user. The varied screen properties are achieved with
hardware.
[0009] U.S. Pat. No. 7,843,439, entitled "Touch Detection for a
Digitizer," assigned to N-Trig Ltd., the contents of which is
incorporated herein by reference, describes a detector for
detecting both a stylus and touches by fingers or like body parts
on a digitizer sensor. The detector typically includes a digitizer
sensor with a grid of sensing conductive lines, a source of
oscillating electrical energy at a predetermined frequency, and
detection circuitry for detecting a capacitive influence on the
sensing conductive line when the oscillating electrical energy is
applied, the capacitive influence being interpreted as a touch. The
detector is capable of simultaneously detecting multiple finger
touches and/or stylus touch.
[0010] U.S. Application Publication No. 2008-0012838 entitled "User
Specific Recognition of Intended User Interaction with a
Digitizer," U.S. Application Publication No. 2006-0012580 entitled
"Automatic Switching for a Dual Mode Digitizer," and U.S. Pat. No.
8,059,102 entitled "Fingertip Touch Recognition for a Digitizer,"
all assigned to N-Trig Ltd., the contents of all which are
incorporated herein by reference, describe additional methods for
palm rejection.
[0011] U.S. Application Publication No. 2011-0310040, entitled
"System and Method for Finger Resolution in Touch Screens,"
assigned to N-Trig Ltd., the contents of which is incorporated
herein by reference, describes a method for detecting an area on a
digitizer sensor that is touched with a plurality of fingers or
other objects in close proximity to each other and identifying the
location of each finger touch in the area detected. It is described
that matrix defining ratios between voltage level measured in
association with each junction of a digitizer sensor when the
junction is touched and a voltage level measured in association
with each corresponding junction when the junction is untouched is
used to detect touch. It is further described that the location of
each touch in the area detected is determined by applying a series
of thresholds on the ratios defined over the touch area and
comparing results obtained at the different threshold levels.
SUMMARY OF THE INVENTION
[0012] An aspect of some embodiments of the present invention is
the provision of a method for identifying input provided by a palm,
hand, arm, fingers and/or other body parts not intentionally being
used to provide input to a touch sensitive digitizer, and
distinguishing such input from intentional fingertip inputs.
Optionally, both intended and unintended input to a digitizer
sensor may include one or more of input by touch and input by
hovering. Typically, the unintended input is obtained from an
object that is larger, e.g. substantially larger than an object
used for intended input, e.g. finger tip or stylus tip input.
According to some embodiments of the present invention, a potential
area in which palm input is expected is defined in relation to an
identified intentional input provided by a fingertip touch and/or a
stylus. In some exemplary embodiments, input detected within
potential area in which palm input is expected is invalidated as an
intentional fingertip touch interaction. Optionally inadvertent
and/or undesired input from a hand while accompanied with
intentional input, e.g. from a fingertip and/or stylus, is detected
and/or tracked and used to provide additional information that is
used by the digitizer system and/or host to improve recognition
and/or functionality.
[0013] As used herein, the terms `inadvertent input` and `palm
input` refer to input provided by any one or more of a palm, hand,
wrist, arm, knuckle, fist and thumb and/or folded fingers while not
intentionally being used to provide input, such as may typically
occur together with intended input provided with a fingertip and/or
hand held object, e.g. a stylus. As used herein, the term
`inadvertent input` also includes other parts of the body that may
typically come in contact with a touch screen. One example of such
a body part is an ear or a cheek which may typically come into
contact with a smart phone including a touch screen. Additionally,
the terms `inadvertent input` and `palm input` also include the
aforesaid input while not accompanied by an intended input.
[0014] According to an aspect of some embodiments of the present
invention, there is provided a method for identifying inadvertent
input provided to a digitizer sensor, the method comprising:
sampling output over one or more sampling periods; identifying a
location of intentional input to the digitizer sensor from the
output sampled over the one or more sampling periods; identifying
an area of potential palm input having a defined spatial relation
to the location of the intentional input; and classifying output
detected in the area of the potential palm input as output
potentially provided inadvertently, wherein the output classified
is sampled over one or more sampling periods other than the one or
more sampling periods from which the area of potential palm input
is identified.
[0015] Optionally, the area of potential palm input is updated over
subsequent sampling periods and wherein the output is classified
over the subsequent sampling periods.
[0016] Optionally, the area of potential palm input is defined as a
dynamic area that is updated as the location of the intentional
input is updated.
[0017] Optionally, the intentional input to the digitizer sensor is
input provided by a stylus.
[0018] Optionally, the method comprises determining an orientation
of the stylus and identifying the area of potential palm input in
relation to the orientation of the stylus.
[0019] Optionally, determining an orientation of the stylus
includes determining a three dimensional orientation of the stylus
with respect to the digitizer sensor as identified.
[0020] Optionally, the area of potential palm input in relation to
the orientation of the stylus is defined as an area on the
digitizer sensor covered by the stylus and a hand holding the
stylus.
[0021] Optionally, the method comprises determining a moving
direction of the intentional input and defining the area of
potential palm input in relation to the moving direction.
[0022] Optionally, the intentional input is input provided by one
or more fingertip touches.
[0023] Optionally, the method comprises determining an angle of at
least one fingertip touch with respect to an axis of the digitizer
sensor; and defining the area of potential palm input in relation
to the detected angle of at least one fingertip touch.
[0024] Optionally, the method comprises identifying one or more
features of the at least one fingertip touch; identifying a hand
structure from the one or more features; and determining the area
of potential palm input responsive to the identified hand
structure.
[0025] Optionally, the method comprises determining the output
using more than sensing configuration; identifying an interaction
area on the digitizer sensor that is larger than a threshold size
area for identifying palm input; and defining the area of potential
palm input in the vicinity of the interaction area that is larger
than a threshold size area for identifying palm input.
[0026] Optionally, the method comprises sampling output using a
self-capacitance detection method and a mutual capacitance
detection method, and determining the area of potential palm input
responsive to output obtained from both the self-capacitance
detection method and the mutual capacitance detection method.
[0027] Optionally, the method comprises determining a size of an
area over which the intentional input is provided over a plurality
of sampling periods, and invalidating the input as intentional
input responsive to the rate in the change of size being larger
than a pre-defined rate.
[0028] Optionally, input detected within the area of potential palm
input is refrained from being reported to the host.
[0029] Optionally, input detected within the area of potential palm
input is reported to the host as inadvertent input.
[0030] Optionally, input detected within the area of potential palm
input is associated with a reduced level of confidence that the
input is an intentional input provided by fingertip touch.
[0031] Optionally, the intentional input to the digitizer sensor is
one of touch input and hover input.
[0032] Optionally, a size of the area of potential palm input is a
pre-defined.
[0033] Optionally, the pre-defined size is user specific.
[0034] According to an aspect of some embodiments of the present
invention, there is provided a method for identifying inadvertent
input provided to a digitizer sensor, the method comprising:
sampling output over at least two sampling periods; determining an
area of input based on the sampled output; determining a change in
size of the area of input over the at least two sampling periods;
and invalidating the input as intentional input responsive to the
change of size being larger than a pre-defined threshold.
[0035] According to an aspect of some embodiments of the present
invention, there is provided a method for detecting finger touch to
a digitizer sensor, the method includes: defining a threshold level
of output for identifying a presence of a finger over the digitizer
sensor; determining a change in the digitizer sensor's impedance to
ground; and adjusting the threshold level response to the change in
the digitizer sensor's impedance to ground.
[0036] Optionally, the method includes defining ratios between
voltage level measured in association with each junction of the
digitizer sensor when the junction is touched and a voltage level
measured in association with each corresponding junction when the
junction is untouched is used to detect touch; and applying the
threshold on the ratios to detect the presence of the finger over
the digitizer sensor.
[0037] Implementation of the method and/or system of embodiments of
the invention can involve performing or completing selected tasks
manually, automatically, or a combination thereof. Moreover,
according to actual instrumentation and equipment of embodiments of
the method and/or system of the invention, several selected tasks
could be implemented by hardware, by software or by firmware or by
a combination thereof using an operating system.
[0038] For example, hardware for performing selected tasks
according to embodiments of the invention could be implemented as a
chip or a circuit. As software, selected tasks according to
embodiments of the invention could be implemented as a plurality of
software instructions being executed by a computer using any
suitable operating system. In an exemplary embodiment of the
invention, one or more tasks according to exemplary embodiments of
method and/or system as described herein are performed by a data
processor, such as a computing platform for executing a plurality
of instructions. Optionally, the data processor includes a volatile
memory for storing instructions and/or data and/or a non-volatile
storage, for example, a magnetic hard-disk and/or removable media,
for storing instructions and/or data. Optionally, a network
connection is provided as well. A display and/or a user input
device such as a keyboard or mouse are optionally provided as
well.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Some embodiments of the invention are herein described, by
way of example only, with reference to the accompanying drawings.
With specific reference now to the drawings in detail, it is
stressed that the particulars shown are by way of example and for
purposes of illustrative discussion of embodiments of the
invention. In this regard, the description taken with the drawings
makes apparent to those skilled in the art how embodiments of the
invention may be practiced.
[0040] In the drawings:
[0041] FIG. 1 is an exemplary simplified block diagram of a
digitizer system that can be used in some embodiments of the
present invention;
[0042] FIG. 2 is a schematic illustration of an exemplary mutual
capacitance detection method that can be used in some embodiments
of the present invention;
[0043] FIGS. 3A and 3B are schematic illustrations of a
self-capacitance detection method that can be used in some
embodiments of the present invention;
[0044] FIG. 4 is a schematic illustration of a potential palm input
area that is defined based on position of a stylus interacting with
a digitizer sensor in accordance with some embodiments of the
present;
[0045] FIG. 5 is a simplified flow chart of an exemplary method for
identifying a potential palm input area during stylus interaction
with a digitizer sensor in accordance with some embodiments of the
present invention;
[0046] FIGS. 6A and 6B are exemplary schematic illustrations of
hands interacting with a digitizer sensor and corresponding output
detected on the digitizer sensor based on which a potential palm
input area is defined in accordance with some embodiments of the
present;
[0047] FIG. 7 is a simplified flow chart of an exemplary method for
identifying a potential palm input area based on hand mapping
during finger touch interaction with a digitizer sensor in
accordance with some embodiments of the present invention;
[0048] FIGS. 8A, 8B and 8C are schematic illustrations of a finger
interacting with a digitizer sensor and corresponding output
obtained during mutual capacitance detection and self-capacitance
detection respectively in accordance with some embodiments of the
present;
[0049] FIG. 9 is a simplified flow chart of an exemplary method for
identifying a potential palm input area using output obtained from
self-capacitance detection method in accordance with some
embodiments of the present invention;
[0050] FIG. 10 is a schematic illustration of a fingertip touch
area and a palm touch area as detected over three consecutive
sampling periods in accordance with some embodiments of the present
invention;
[0051] FIG. 11 is a simplified flow chart of an exemplary method
for identifying palm input and/or other inadvertent input based on
changes in a touch area over a plurality of sampling periods in
accordance with some embodiments of the present invention; and
[0052] FIG. 12 is a simplified flow chart of an exemplary method
for adjusting a threshold level for detection based on variations
in a system's impedance to ground in accordance with some
embodiments of the present invention.
DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION The present
invention relates to multi-touch digitizer systems, and more
particularly to recognition of palm input to a multi-touch
digitizer.
[0053] According to an aspect of some embodiments of the present
invention there is provided a method for identifying areas on a
digitizer sensor over which palm input is expected. According to
some embodiments of the present invention, areas on a digitizer
sensor over which palm input is expected is defined in relation to
an identified location of intentional input, e.g. stylus and/or
fingertip touch. According to some embodiments of the present
invention, the identified area over which palm input is expected is
a dynamic area that moves as the location of intentional input is
detected to move, and is optionally maintained as long as the
identified intentional input is present, e.g. over a plurality of
sampling periods.
[0054] According to some embodiments of the present invention, an
assumption is made that intentional input within the defined area
over which palm input is expected is unlikely. In some exemplary
embodiments, input detected within that area is ignored, e.g. not
reported, classified as palm input, and/or associated with a low
confidence level that such input is an intentional fingertip
interaction, e.g. an intentional fingertip hover or touch
interaction.
[0055] Optionally, system and method for invalidating output
obtained from a region classified as a region of unintended input
is similar to methods described for example in International Patent
Application No. PCT/IL2012/050048 filed on Feb. 15, 2012 assigned
to N-Trig Ltd., the contents of which is incorporated herein by
reference.
[0056] In some exemplary embodiments, the defined area over which
palm input is expected is determined from output obtained when
using a sensing configuration that is more sensitive to hovering.
In some embodiments of the present invention, the defined area over
which palm input is expected is defined based on output obtained
from a self-capacitance detection method together with output
obtained from when using a mutual capacitance detection method. In
some exemplary embodiments, the defined area over which palm input
is expected is determined based on changes in touch areas over a
plurality of sampling cycles.
[0057] Optionally, during stylus interaction, a three dimensional
orientation of the stylus is detected and used to determine the
defined area over which palm input is expected.
[0058] Optionally, a direction of stylus movement is used to
determine the defined area over which palm input is expected.
Optionally, input received in the defined area over which palm
input is expected in one or more sampling periods preceding and/or
following a sampling period(s) is invalidated. Optionally, the
methods described herein are used together with other known methods
of palm detection to enhance an ability to differentiate between
intentional and inadvertent input provided to a digitizer
sensor.
[0059] For purposes of better understanding some embodiments of the
present invention, as illustrated in FIGS. 4-11 of the drawings,
reference is first made to the construction and operation of an
exemplary digitizer sensor and associated detection methods as
shown in FIGS. 1-3. Reference is first made to FIG. 1 showing an
exemplary simplified block diagram of a digitizer system that can
be used in some embodiments of the present invention. The digitizer
system 100 may be suitable for any computing device that enables
touch and/or hover input between a user and the device, e.g. mobile
and/or desktop and/or tabletop computing devices that include, for
example, FPD screens. Examples of such devices include Tablet PCs,
pen enabled lap-top computers, tabletop computers, PDAs or any hand
held devices such as palm pilots and mobile phones or other devices
that facilitate electronic gaming. According to some embodiments of
the present invention, the digitizer system comprises a sensor 26
including a patterned arrangement of conductive lines 18, which is
optionally transparent, and which is typically overlaid on a FPD.
Typically sensor 26 is a grid based sensor including horizontal and
vertical conductive lines forming a first and second axis.
[0060] According to some embodiments of the present invention,
circuitry is provided on one or more PCB(s) 30 positioned around
and/or in the vicinity of sensor 26. According to some embodiments
of the present invention, one or more Application Specific
Integrated Circuits (ASICs) 16 connected to outputs of the various
conductive lines 18 in the grid is positioned on PCB(s) 30.
Typically, ASICs 16 function to process the received signals at a
first processing stage and to sample the sensor's output into a
digital representation. The digital output signal is forwarded to a
digital unit 20, e.g. digital ASIC unit also on PCB 30, for further
digital processing. According to some embodiments of the present
invention, digital unit 20 together with ASIC 16 serves as the
controller of the digitizer system and/or has functionality of a
controller and/or processor. Output from the digitizer sensor is
forwarded to a host 22 via an interface 24 for processing by the
operating system or any current application. Optionally, at least
part of the processing is performed by host 22.
[0061] According to some embodiments, digital unit 20 produces and
sends a triggering pulse to at least one of the conductive lines
18. Typically the triggering pulses and/or signals are analog
pulses and/or oscillating signals. In some exemplary embodiments,
finger touch detection is facilitated when sending a triggering
pulse to the conductive lines. Typically, the presence of a finger
and/or fingertip 46 decreases the triggering signal by 5-30% since
finger 46 typically drains current from conductive lines 18 to
ground. Detection of a token 45 is also facilitated when sending a
triggering pulse to conductive lines 18 and typically increases
amplitude of the triggering signal. In some exemplary embodiments,
amplitude of the signal within a bandwidth of 18-40 KHz or 18-200
KHz is examined to detect fingertip and/or token touch. According
to some embodiments of the present invention, a stylus 44
additionally interacts with digitizer sensor 26 by emitting a
signal that can be picked up by one or more conductive lines 18.
Triggering conductive lines 18 is typically not required for stylus
detection. Typically a frequency of a signal emitted by stylus 44
is distinguishable from the triggering signal used for finger
detection.
[0062] Reference is now additionally made to FIG. 2 showing a
schematic illustration of an exemplary mutual capacitance detection
method that can be used in some embodiments of the present
invention. According to some embodiments of the present invention,
a mutual capacitance touch detection method is used for identifying
location of one or more fingertip touches 41 and/or capacitive
objects (token) at the same time (multi-touch). During mutual
capacitance detection digital unit 20 typically produces and sends
AC signal 60 to each of conductive lines 18 along one axis in turn
(the driving lines) and ASIC 16 in turn detects output from
conductive lines 18 along the other axis (the passive lines).
Output 65 is simultaneously sampled from each of the passive lines
in response to each transmission of the triggering signal, e.g.
interrogation signal to a driving line. Typically at each junction,
e.g. junction 40 in digitizer sensor 26 a certain capacitance
exists between orthogonal conductive lines so that a trigger pulse
that includes an oscillating signal is transferred by virtue of
capacitance to a conductive line with which a junction is formed.
When finger 46 touches digitizer sensor 26 at or over an area 41
where triggering signal 60 is induced, the capacitance between the
driving line and the passive lines proximal to the touch position
changes and signal 60 crossing to the passive line produces a lower
amplitude signal 65, e.g. lower in reference to base-line
amplitude. Base-line amplitude is amplitude recorded while no user
interaction is present. Optionally, a sensing configuration, e.g.
amplitude threshold level for detection is defined to be lower than
the base-line level by a pre-defined amount. Typically, the
presence of a finger decreases the amplitude of the coupled signal
by about 15-30% since the finger typically drains current from the
lines to ground. Optionally, a finger hovering at a height of about
1-2 cm above the display can also be detected.
[0063] Reference is now additionally made to FIGS. 3A and 3B
showing schematic illustrations of a self-capacitance detection
method that can be used in some embodiments of the present
invention. According to some embodiments of the present invention,
a self-capacitance touch detection method is used for detecting
interaction of one or more fingertips and/or tokens with digitizer
sensor 26. Optionally, during self-capacitance touch detection,
stylus input is also determined. During self-capacitance detection,
digital unit 20 typically produces and simultaneously sends AC
signal 60 to a plurality of conductive lines 18 and/or to all
conductive lines 18 along one axis, and ASIC 16 detects output 65
from the same conductive lines 18 that are triggered (FIG. 3A).
When finger 46 touches digitizer sensor 26 at a certain position 41
where triggering signal 60' is induced, the capacitance formed
between the finger and the conductive lines 18 in the vicinity of
the finger produces a lower amplitude output signal 65, e.g. lower
in reference to base-line amplitude. Based on output 65, conductive
lines 18 along one axis of digitizer sensor 26 that are proximal to
finger 46 are determined. Subsequently, digital unit 20 produces
and simultaneously sends AC signal 60' to each of conductive lines
18 along the other axis and ASIC 16 detects output 65' from the
same conductive lines 18 that are triggered (FIG. 3B). Based on
output 65', conductive lines 18 along the other axis of digitizer
sensor 26 that are proximal to finger 46 are determined. Positions
of touch are determined by combining information obtained from each
of the axes.
[0064] Optionally, digital unit 20 simultaneously triggers all
conductive lines 18 along both axes and ASICS 16 substantially
simultaneously detect output 65 and 65' from all conductive lines
18 along both axes. It is noted that although the triggering signal
is shown to be introduced on one end of conductive lines 18 and the
output is shown to be detected from an opposite end of conductive
lines 18, this may not necessarily be the case. Optionally,
triggering and detection is applied on a same end of conductive
lines 18.
[0065] Typically, the self-capacitance detection method is
advantageous in that it does not require scanning and therefore
provides faster detection with fewer computations as compared to
the mutual capacitance detection method. An additional advantage of
self-capacitance detection is that it is typically more sensitive
to hovering as compared to the mutual-capacitance detection.
However, the self-capacitance detection method is limited in that
locations of more than one fingertip interacting with the digitizer
sensor cannot always be resolved due to ghosting. Ghosting occurs
when more than one option for pairing output obtained from each
axis is possible, and therefore touch location remain ambiguous.
Systems and methods for using both self-capacitance detection and
mutual capacitance detection are described in more detail for
example in U.S. Patent Publication No. US20090251434 entitled
"Multi Touch and Single Touch Detection," assigned to N-Trig Ltd.,
the contents of which is incorporated herein by reference.
[0066] It should be noted that the embodiments of FIGS. 1-3 are
presented as an exemplary "platform" for carrying out the
invention. However in its broadest form, the invention is not
limited to any particular platform and can be adapted to operate on
any digitizer or touch or stylus sensitive display or screen that
accepts and differentiates between two simultaneous user
interactions. Digitizer systems used to detect stylus and/or finger
touch location may be, for example, similar to digitizer systems
described for example U.S. Pat. No. 6,690,156, U.S. Pat. No.
7,292,229 and/or U.S. Pat. No. 7,372,455 all assigned to N-Trig
Ltd., the contents of all of which is incorporated herein by
reference. The present invention may also be applicable to other
digitizer sensor and touch screens known in the art, depending on
their construction.
[0067] Reference is now made to FIG. 4 showing a schematic
illustration of a potential palm input area that is defined based
on position of a stylus interacting with a digitizer sensor and
also to FIG. 5 showing a simplified flow chart of an exemplary
method for identifying a potential palm input area during stylus
interaction with a digitizer sensor, both in accordance with some
embodiments of the present invention. At times while a user
interacts with a digitizer sensor 26 using stylus 44, input from a
hand 48 holding stylus 44 may be picked up by digitizer sensor 26.
At times, input from hand 48 may be confused with intentional input
provided by fingertip touch interacting with the digitizer together
with stylus 44. The present inventors have found that information
regarding location of stylus 44 and/or its three dimensional
orientation can be used to define and/or predict an area 450 in
digitizer sensor 46 covered by hand 48 holding the stylus. The
present inventors have noted that intentional fingertip touch input
is unlikely in area 450 covered by hand 48 holding a stylus and
therefore any input received in that area may be assumed to be palm
input and/or other inadvertent input.
[0068] According to some embodiments of the present invention,
during interaction with a digitizer sensor 26, a stylus 44 is
identified and its coordinates are detected (block 505).
Interaction with digitizer sensor 26 may be by touch and/or hover.
Typically, a potential location for palm input, e.g. area 450
covered by hand 48 is defined in relation to a current tip location
of stylus 44 and the location is updated as the tip location
changes. According to some embodiments of the present invention, a
direction of movement of the stylus is also detected (block 510).
As the tip locations moves, the defined location for potential palm
input will be redefined and/or moved along in the direction that
the tip moves. Optionally, a direction of tip movement is used to
predict a potential location of palm input. For example, while a
stylus moves from left to right to draw a line 25, it can be
expected that hand 48 will be to the right of the movement.
Alternatively, the opposite may be true for a particular user, e.g.
a left-handed user and/or a particular language of interaction.
Optionally, the determination is user-specific based on known
parameters of the user.
[0069] Optionally in addition to location, orientation of the
stylus is also determined and tracked (block 515). In some
exemplary embodiments a tilt sensor 443 embedded in stylus 44
provides information regarding stylus tilt. Optionally, stylus 44
transmits a signal from more than one location along its length and
three dimensional orientation of stylus 44 is determined from a
plurality of inputs provided by stylus 44. Optionally stylus 44 may
be similar to a stylus disclosed in International Patent
Application No. WO2011154950, entitled "Orientation Detection with
a Digitizer," assigned to N-Trig Ltd., the contents of which is
incorporated herein by reference.
[0070] According to some embodiments of the present invention,
location of stylus 44 and one or more of stylus tilt and direction
of stylus movement is used to define a potential palm input area
(block 520). A size and/or orientation of the potential palm input
area may be based on user-specific information and/or based on
averages taken from a plurality of users. According to some
embodiments of the present invention, any input obtained within the
defined potential palm input area is invalidated as input provided
from a fingertip touch (block 525). Typically, the defined
potential palm input area is valid for a pre-defined period of time
and/or until the defined potential palm input area is updated.
Optionally, the defined potential palm input may be updated based
on movement of associated fingertip touch, e.g. moved in relation
to the fingertip touch 41. Optionally, updating of the defined
potential palm input region may be additionally and/or
alternatively performed with one or more methods described
herein.
[0071] Optionally, input within region 450 is characterized and
information regarding input in region 450 is provided to a host,
e.g. provided in addition to coordinates of stylus 44. Optionally,
palm input during stylus interaction is analyzed and used for
signature verification and/or as additional input. Optionally,
detection parameters, e.g. sensing configuration within region 450
are defined differently to increase the detection sensitivity for
palm input, which typically includes both touch and hover areas.
Optionally, input provided in region 450 is not automatically
invalidated, but instead a confidence level attributed to the input
is set lower than a same input provided in a region outside of
region 450.
[0072] Reference is now made to FIGS. 6A and 6B showing exemplary
schematic illustrations of hands interacting with a digitizer
sensor and corresponding output detected on the digitizer sensor
based on which potential palm input areas are defined, and to FIG.
7 showing a simplified flow chart of an exemplary method for
identifying a potential palm input area based on hand mapping
during finger touch interaction with a digitizer sensor in
accordance with some embodiments of the present invention.
According to some embodiments of the present invention, position
and/or orientation of one or more fingers 46 touching digitizer
sensor 26 are examined based on one or more fingertip touch areas
41 detected on digitizer sensor 26 (FIG. 6B). According to some
embodiments of the present invention, during operation, touch
points on the digitizer are identified (block 705) and segmented
into touch regions (block 710). Optionally, the touch regions are
classified as fingertip input region 41 and palm input region 49,
based on size, shape and/or amplitude output of the regions.
Optionally, segmentation is performed using more than one threshold
level for detection and/or sensing configuration so that larger
palm input areas 49 that include both touch and hover areas of a
palm can be combined into larger groups. For example, one set of
touch input points 411 (shown as large dots) may be obtained using
one sensing configuration for detection, while additional touch
points 412 (shown as small dots) may be obtained when adjusting the
sensing configuration, e.g. increasing the threshold level for
detection for finger touch detection. Optionally, segmentation is
performed with methods described in incorporated U.S. Application
Publication No. 2011-0310040.
[0073] According to some embodiments of the present invention,
spatial parameters of the touch areas 41 classified as fingertip
touch, e.g. size, shape and/or angle are determined (block 715).
Typically input provided by one or more finger touches has an
oblong shape, e.g. an ellipse while palm input may have a banana
curved shaped and/or an irregular shape.
[0074] Optionally, an angle a that a major axis of the oblong shape
makes with an axis of the digitizer is detected. Size of each touch
area and relative positioning between the touch areas may also be
detected and used to map out the orientation of the hand providing
the fingertip touches. Optionally, the touch areas are segmented
into different hands based on the analysis and more than one
potential palm area is defined. According to some embodiments of
the present invention, potential palm areas are defined based on
analysis of hand position and/or detection of palm input areas
(block 720). Typically, input provided in a potential palm input
region is invalidated as an intentional fingertip interaction for a
pre-defined period of time and/or until an updated potential palm
input region (725). Input provided in the defined potential palm
input region can be ignored, e.g. not reported to the host, or can
be reported to the host and labeled as input other than intentional
fingertip touch input. Optionally, the defined potential palm input
may be updated based on movement of associated fingertip touch,
e.g. moved together with the fingertip touch 41. Optionally,
updating of the defined potential palm input region may be
additionally and/or alternatively performed with one or more
methods described herein. Typically although not necessarily, the
potential palm input area that is defined is larger than an
identified region of palm input. Optionally, the potential palm
input area has a predefined size. Optionally the size of the palm
input area is determined based on a detected orientation of the
hand and/or based on pre-defined parameters for a particular user
that is defined in a calibration procedure.
[0075] Reference is now made to FIGS. 8A, 8B and 8C showing
schematic illustrations of a finger interacting with a digitizer
sensor and corresponding output obtained during mutual capacitance
detection and self capacitance detection respectively, and to FIG.
9 showing a simplified flow chart of an exemplary method for
identifying a potential palm input region using output obtained
from self-capacitance detection method, all in accordance with some
embodiments of the present invention. According to some embodiments
of the present invention, a digitizer system providing multi-touch
detection uses both a self capacitance detection method and a
mutual capacitance detection method for identifying interaction by
a finger 46 and/or other capacitive object with a digitizer sensor.
Typically, output based on mutual capacitance detection 812 (FIG.
8B) can distinguish between multiple touches occurring at the same
time, e.g. without ghosting, but is typically less sensitive to
hovering.
[0076] On the other hand, while output based on self capacitance
detection 816 (FIG. 8C) may suffer from ghosting effects, it is
typically more sensitive to hover. It is noted that in FIGS. 8B and
8C, different amplitude of output is schematically represented as
different sized dots with the larger dots representing a higher
detection level. The present inventors have found that the
increased sensitivity to hover obtained using self capacitance
detection can be used to help identify a general area of palm
input. Since the palm is typically not flat, additional information
regarding hovering portions of the palm may help identify an
expanded area affected by palm input 49 obtained from a palm 48.
According to some embodiments of the present invention, during
operation of a digitizer sensor, both self capacitance output is
sampled (block 906) and mutual capacitance output is sampled (block
911). According to some embodiments of the present invention,
outputs obtained from both detection methods are compared and used
to identify fingertip touch input area 41 and palm input area 49
(block 916). Optionally, a potential palm input area 450 is
identified based on identified palm input (block 920). Typically
although not necessarily, the potential palm input area that is
defined is larger than an identified region of palm input.
Optionally, the potential palm input area has a predefined size.
Optionally the size of the palm input area is determined based on a
detected orientation of the hand and/or based on pre-defined
parameters for a particular user that is defined in a calibration
procedure. Typically, input provided in a potential palm input
region is invalidated as an intentional fingertip interaction for a
pre-defined period of time and/or until an updated potential palm
input region is determined (block 925). Input provided in the
defined potential palm input region can be ignored, e.g. not
reported to the host or can be reported to the host and labeled as
input other than intentional fingertip touch input.
[0077] Optionally, the defined potential palm input may be updated
based on movement of associated fingertip touch, e.g. moved in
relation to the fingertip touch 41. Optionally, updating of the
defined potential palm input region may be additionally and/or
alternatively performed with one or more methods described
herein.
[0078] Reference is now made to FIG. 10 showing schematic
illustration of a fingertip touch area and a palm touch area as
detected over three consecutive sampling periods and FIG. 11
showing a simplified flow chart of an exemplary method for
identifying palm input based on changes in a touch area over a
plurality of sampling periods, all in accordance with some
embodiments of the present invention. The present inventors have
found that at the onset of a touch event, palm touch may cover a
small area such as is typically covered by a fingertip touch
interaction, and therefore may be confused with a fingertip touch
input. However, as the touch area expands over subsequent sampling
periods, differences in touch area typically develop. The present
inventors have found that the rate of expansion of palm touch area
49 is typically greater than that of fingertip touch area 41 and by
examining the rate of expansion, palm input can be distinguished
from touch input. The present inventors have found that palm input
can be detected at an earlier stage based on rate of expansion as
compared to size of input area. According to some embodiments of
the present invention, size of a touch area is tracked over a
plurality of consecutive samples 905, 910 and 915 (block 1005). It
is noted that although output over three samples is shown for
exemplary purposes, any number of samples may be used to determine
a rate of expansion of a touch area, e.g. output over two sampling
periods and/or over 3-10 sampling periods or more, may be used.
Optionally, expansion is tracked over every other sampling period
or every third to fifth sampling period. Typically at the onset of
touch, a size of a touch is smallest at the earliest sampling
period 905 and the size of the touch increases over a plurality of
sampling periods as a finger and/or hand is pressed further toward
the digitizer sensor. According to some embodiments of the present
invention, a rate of increase in size is tracked and used as an
indicator to classify a touch area as a fingertip touch area 41 or
a palm input area 49 (block 1010). Optionally, a rate of change
typical of palm input is pre-defined based on a calibration
procedure or parameters defined in a manufacturing site, e.g. based
on experimental data. Optionally, joining of one or more touch
areas may be tracked over a plurality of sampling periods and used
to identify palm input. According to some embodiments of the
present invention, palm input is defined for a rate of change above
a pre-defined level (block 1015). According to some embodiments of
the present invention, a detected palm input is reported to a host
(1020). Optionally, the digitizer system maintains a list of
previous reports to determine if classification of touch area has
changed due to detected features of the touch area over time. In
some exemplary embodiments when a change in classification is
determined, instructions to re-classify a specific past touch event
are provided to the host. Optionally, a potential palm input region
in the vicinity of the identified palm input region is defined.
Optionally, the methods described herein in reference to FIGS. 10
and 11 is used to differentiate between intentional input and
inadvertent input, and a rate of change typical of a specific
unintentional input other than a palm, e.g. an ear or cheek is
pre-defined based on a calibration procedure or parameters defined
in a manufacturing site, e.g. based on experimental data.
[0079] According to some embodiments of the present invention, a
potential palm input area once defined using one or more methods
described herein, is used to invalidate input detected and within
the potential palm input over one or more previous and/or
subsequent sampling periods. Optionally, input detected within the
potential palm input area is automatically invalidated as a
possible intentional fingertip interaction without further analysis
of that input. Optionally, the potential palm input area is
adjusted to move along with a stylus and/or fingertip touch area,
as long as the stylus and/or fingertip touch is maintained on the
digitizer. It is noted that although the potential palm input area
is used to invalidate an intentional fingertip touch interaction,
input in the potential palm input area may still be used and/or
reported to a host, e.g. as palm input. Optionally, input from the
potential palm input area can be used to provide additional
information to the host that can be used for example for signature
verification and/or to enhance functionality of the digitizer.
Optionally, input provided in potential palm input area is not
automatically invalidated, but instead a confidence level
attributed to the input is much lower than a same input provided in
a region outside of potential palm input region.
[0080] It is noted that although the blocks in the flow charts
shown in FIGS. 5, 7 and 9 appear one after the other, it is clear
to a person that is skilled in the art that at least some of the
blocks in FIGS. 5, 7 and 9 may be executed in parallel.
[0081] Typically, the presence of a finger and/or fingertip 46
decreases the measured signal by 5-30% relatively to a measurement
in the absence of touch, since finger 46 typically drains current
from conductive lines 18 to ground. The present inventors have
found that the degree by which the signal is decreased due to the
presence of finger 46 depends on the sensor's impedance to ground.
The present inventors have found that a digitizer sensor that has
low impedance to ground, e.g. directly connected to ground is
typically more sensitive to capacitive touch than a digitizer
sensor that has higher or high impedance to ground since the
touched areas may be more distinct. The present inventors have also
found a digitizer sensor's sensitivity to touch can change during
an operation session in response to changes in its impedance to
ground. For example a mobile device including a digitizer sensor
may provide higher sensitivity to touch while positioned on a large
metal table and lower sensitivity to touch while positioned on a
glass table. In another example, sensitivity to touch may be
increased in response to a user holding the mobile device.
[0082] Reference is now made to FIG. 12 showing a simplified flow
chart of an exemplary method for adjusting a threshold level for
detection based on variations in a system's impedance to ground. In
some exemplary embodiments, the threshold level for detection is
defined based on predicted and/or known impedance to ground (block
1100). In some exemplary embodiments, for digitizer systems
integrated with a stationary computing device, e.g. a personal
computer, a high threshold level is defined since the device is
expected to have low impedance to ground and therefore a signal in
response to finger touch is expected to be relatively high and/or
strong. In some exemplary embodiments, for digitizer systems that
are part of a mobile computing device, e.g. a mobile telephone, a
lower threshold level is defined since the device is expected to
have higher impedance to ground and therefore a signal in response
to finger touch is expected to be lower. In some exemplary
embodiments, the threshold for detecting touch is not applied
directly on the output detected by the digitizer but rather on
ratios between voltage level measured in association with each
junction of a digitizer sensor when the junction is touched and a
voltage level measured in association with each corresponding
junction when the junction is untouched, e.g. in the absence of
touch. Methods for defining the ratio is described in detailed for
example in incorporated U.S. Application Publication No.
2011-0310040.
[0083] Optionally, the impedance level to ground and/or changes in
the impedance to ground is monitored and/or detected over a course
of operation with the digitizer sensor (block 1110) and the
threshold level for detection is updated based on the detected
impedance level and/or the detected changes (block 1120).
[0084] The terms "comprises", "comprising", "includes",
"including", "having" and their conjugates mean "including but not
limited to".
[0085] The term "consisting of" means "including and limited
to".
[0086] The term "consisting essentially of" means that the
composition, method or structure may include additional
ingredients, steps and/or parts, but only if the additional
ingredients, steps and/or parts do not materially alter the basic
and novel characteristics of the claimed composition, method or
structure.
[0087] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable sub-combination
or as suitable in any other described embodiment of the invention.
Certain features described in the context of various embodiments
are not to be considered essential features of those embodiments,
unless the embodiment is inoperative without those elements.
* * * * *